There are many instances where a wellbore has been formed down through a payzone and satisfactory production realized for a substantial length of time. However, as time progresses, for one reason or another, the well commences making excess water while the hydrocarbon production diminishes. In this instance, the formation surrounding the perforations is comprised of a low water strata, which is the hydrocarbon production part of the formation, and a high water strata, which accounts for most of the water produced by the well. The low water and high water strata meet or contact one another along an interface. Usually the low water, oil bearing strata is located above the high water strata.
In order to increase the hydrocarbon production of the above described wellbore, acidizing and fracturing is often attempted; however, the acid along with the propping agent flows along the path of least resistance, which is usually into the high water strata where the acid probably does more harm than good. When a marginal well, such as the one described above, fails to respond to this type of well stimulation, it is usually thought best to abandon the well because of the economics involved.
It would be desirable to be able to force acid and propping agents into the hydrocarbon producing part of the formation, where the formation can be fractured and acid treated; and, the fractures propped open with suitable propping agents, thereby increasing the production of the wellbore. It would be desirable to be able to form a barrier along the water/oil interface between the low water and high water strata, thereby enabling the acid treatment to be carried out and effected on the hydrocarbon producing part of the formation in contrast to the water producing part of the formation. Such a desirable method is the subject of the present invention.